Boiler construction



G. WELTER LER CONSTRUCTION Dec. 11, 1934.

Filed Sept. 20, 1932 2 Sheets-Sheet 1 INVENTOR BY 6057/1145 WEJER 9 ZATTORNEY Dec. 11, 1934. G WELTER BOILER CONSTRUCTION 1932 2 Sheets-Sheet2 Filed Sept. 20

IN VEN TOR 6 1/5 7/1 v5 WA'L TM 9 712 A TTORNEYS Patented Dec. 11, 1934PATENT OFFICE BOILER CONSTRUCTION Gustave Welter, New Haven, Conn.,assignor to The Bigelow company, New Haven, Conn., a corporation ofConnecticut Application September 20, 1932, Serial No. 633,943

6 Claims.

This invention relates to an improved boiler construction. Theimprovement as shown in its preferred form is particularly designed forelectrically heated boilers adapted for use on railroad trains. Whenelectric engines are used to draw a string of passenger cars, steam heatis wanted for the cars. A steam boiler can be carried in the electrictrain, heated by electricity, and the steam sent through the ordinarycar heating pipes. This is the specific use for which the boiler shownin the drawings is designed and to which my improvement in its firstembodiment was adapted. While I will describe the improvement inconnection with a boiler for such use, I wish to point out that it maybe applied in other specific and analogous situations.

An improved feature of the boiler is in the means by which a controlledcirculation of the water is maintained under diflicult requirements. Forexample, a boiler mounted in an electric train as an accessory apparatusis subject to requirements not met in ordinary stationary situations.There is the question of space limitations and the movements of thetrain to be considered.

Among the various features of the invention are those that are relatedto this problem of adapting the boiler for train use.

Other features not particularly related to train use will be disclosedand claimed.

In the drawings,

Fig. l is an. elevation of a cylindrical boiler (with some interiorparts shown dotted and insulation only indicated) to which my inventionhas beenapplied in one specific form;

Fig. 2 is a section on line 22 of Fig. 1, but to avoid mere duplicationonly a few of the many interior parts of the boiler are shown;

Fig. 3 is a detail view of parts only indicated by dotted lines in Fig.1 and by section in Fig. 2; and

Fig.4 is a cross-sectional view on line 4-4 of Fig. 3. I p

Without intending to limit the invention in all particulars to apreferred form chosen for illustration I will describe in detail thespecific embodimentof the drawings.

The boiler is made up i a heat insulated cylinder 1' having top andbottom flanged header members 2 and 3. A manhole 4 safety valves 5,handholes 6, level indicator 7, steam pipe connection 8, and water feedvalves 9 are indicated, but form no feature of invention.

' The bottom of the boiler has a suitable flange construction 10 forsolid but easily removable base connection with the floor ofthe electricengine.

The top flange 2 of the boiler shell provides a mounting in theembodiment shown for one hundred and forty heating elements 11. Each ofthese is mounted to be removably supported as indicated by dotted linesin Fig.1. They each eX- tend between the top and bottom headers 2 and 3,being screwed in at the top with an end casting 12 at the bottom havinga socket to receive the centering stud (mounted as a pin in the bottomheader, see Fig. 1) from which the heating 1 element can be lifted whenunscrewed at the top header. The electric heating element per se formsno part of this invention. A suitable type is indicated and the plan ofheating by electric resistance will be clear. The U-shaped wire for this315 resistance is indicated as all below the water level W-W of theboiler, which can be arranged to correspond with any of the three valves9. The heating element above the water level is no part of the activeheating surface. It consists in any suitable support 13 having electricconnections to the active part or wire below the water level. Thearrangement in the boiler of the large number of heating elements (seethe arrangement in Fig. 2) makes a combination with other means which Iwill describe with respect to a feature of the invention.

If the water were heated by the elements 11 in the boiler so fardescribed, there would be no general or controlled, or definitecirculation of v the water so as to brush against the active heatingelements 11 in a desired manner for efficient heat transfer. Theelectric heat would set up a turbulent condition of the water. Themovement would be haphazard and uncontrolled. And this would create acondition whereby some of the heating elements 11 might not have propercontact with the water to effect proper heat transfer, which wouldresult in the heating elements being over-heated, causing rapiddeterioration of these elements.

To provide a novel means for accomplishing the controlled circulation ofthe water in the boiler and to avoid the objectionable turbulence in theparticular situation I have made a special construction as follows:Referring to Fig. 2, a large number of braces 14, extending between thetop and bottom header members (see Fig. l) are each arranged adjacent aset of heating elements. In general each brace is closely surrounded bysix spaced heating elements. Of course other similar arrangements can bemade but the one shown works well according to the mode of operationthat will be made clear below. A tube 15 for circulation is convenientlymounted, concentric with each brace. As shown in Figs. 1 and 3, the tubemay rest on the bottom header member (or be held by a spider or collarto the brace independently of the bottom member) and be centered thereby a collar 16 on the brace. At this lower end the tube is provided withfour spaced vertical slots or notches 1'7 for :bottom openings to theinterior of the tube, but if held by the brace above the bottom header,these slots are not required. At the top the tube is centered and heldby a spider, 18 that may be attached to brace by a clamping collar orset screw. This provides top openings so a circulation of water asindicated by one line of arrows in Fig. 3 is possible and alikecircula-p tion through each of the four slotted openings at the bottomof the tube. The top openings of the tube are below the waterline (seeFig. 1)

and preferably at about the level on which the top of the active part ofeach heating element is positioned."

- As the water isheated'by the heating elements,

steam bubbles form. Water then rises with the bottom of the boiler so asto repeat the cycle.

The distribution of these circulating tubes in combination with sets ofheating elements grouped: around them is shown in Fig. 2. In that figureonly one segment of the arrangement is shown complete, but it should beunderstood that the same arrangement is made in the other segment tofill the boiler shell 1. The latter figure, together with the detail inFigs. 3 and 4, makes it clear that a very large number of controlledcirculating paths can be set up in the boiler operation by applying theprinciple of the construction disclosed.

The result is that along the length of each heating element 11 an activeflow is induced to brush that element for the best heat exchange and fora rapid controlled recycling of all imvaporized water, resulting in allheating elements being equally active and cooled; thus prolonging theirlife. The remarkable degree to which this takes place will be seen froma consideration of any of the boiler portions such as at the spot markedX in Fig. 2. The six heating elements chosen in this spot or portion setup six paths to return through tube on the brace around which the sixare grouped, and the same six elements set up twelve other paths toreturn through the six tubes arranged around and spaced slightly fromthat part of the surfaces of the same heating elements which do not facethe tube encircled by such elements. And so on through the volume of thewater being heated one can find many more separately controlledsubstituted for the electrical heating elements in such a verticalboiler as shown. They could be positioned where the electrical heatingelements are now shown. The brace rods and circulating cylinders couldbe left as they now are or the cylinders mounted in some other suitablemanner without the brace rods. Of course the fire tubes 'would need afurnace element; "These suggested substitutes are sonwell knownastoneedno drawing.

v It is ordinarily advisable but not necessary in all instances toarrange the size of the circulating tubes so that the volume of thewater and steam bubbles in the rising paths of the boiler is slightlylarger than the volume of the water alone in the paths-(within'thetubes) which return to the bottom of the boiler. This is a matter thatcan be calculated 'for each particular boiler. The definite relation ofthese flow areas, one up and the other down, is one that may desirablyvary in different boiler designs and such variation is intended to beincluded in this disclosure without particular limitations.

The boilerconstruction of this invention in its broadcast aspects may beincorporated in other types of boiler shells than the simple cylindricalone shown. But the one shown lends itself particularly well to theobjects of a pressure unit for a vertical boiler where space limitationsare met in the specific use for which my first embodiment of theinvention'is intended. That is one to be carried on an electriclocomotive. There is the advantage in the specific form shown, asdistinguished from other forms of The cyshells in the followingconsiderations. lindrical shape having its header members braced by thevertical tie rods, gives 3 great bursting strength. Then thedistribution of the vertical tie rods or braces corresponds to mydesired distribution of circulating tubes and their relation to thelarge number of heating elements. And one result of this is that theconstruction and placing of my circulating tubes in the combination canbe accomplished in a most economical manner. The tie rods serve twopurposes; They brace the shell and they position the circulating tubes.The very large number of heating elements and tie rodswith circulatingtubes helps stop the wash of boiler water due to locomotive movements.

While I have indicated that a circulating tube is telescoped over eachbrace rod, this is not necessary. Some of the rods adjacent thecylindrical wall may havethe tubes-omitted. My

intention is to indicate the main idea of the arrangement rather than anecessarily complete sible part of the boiler. I l v I am aware that invertical boiler constructions, means have before been used to controlthe path of the hotwater ri'sing'and colder water falling in theboiler.The present invention consists in the "particular combinations of boilerconstruction by which the water Paths are controlled in a particularlydesirable manner with relation to the heating-elements. Thesecombinations in their various'broadand specific aspects are.pointed outfand'defined in the claims.

I claim asfmy invention; v

1. In a vertical boiler construction of the type having a large group ofvertical heating elements distributedin spaced relation within the waterspace for heat transfenthe combination of means to control the flow ofwater along the heating elementspsaidmeams consisting in a plurality ofopen ended circulating tubes each of which is positioned in the waterspace, adjacent a small set of the heating elements, and in position farenough away from the heating units to serve as a return path for waterthat rises in contact with the heating elements of its set, frees itssteam bubbles at the water level and is ready to return to the bottom ofthe boiler, said tubes having their bottom openings close to the bottomof the water space and their top openings substantially below the boilerwater level, said tubes being distributed over the boiler space insuflicient number to serve substantially all of the heating elements incontrolling the circulation past said elements.

2. In a vertical boiler construction the combination of a group of openended vertical tubes spaced with substantial uniformity in the waterspace of the boiler and each mounted with its bottom opening near thebottom of the boiler and its top opening near but substantially belowthe water level and around each such tube a set of vertical heatingelements spaced from each other and from such tube, the heating elementsforming means to cause rising paths of water on the outside of each tubeand each tube forming a common means for water to return from the risingpaths nearest the tubes to the bottom of the boiler to be recirculated.

3. In a vertical boiler construction the combination of a plurality ofopen ended tubes vertically mounted and wholly in the water space withtheir bottom openings near the boiler bottom and their top openingssubstantially below but near the water level, each tube being outside ofand spaced from the others, there being a suflicient number of tubesdistributed in the boiler to form a large number of independent pathsfor returning water from the top to the bottom of the boiler withsubstantial uniformity and a plurality of vertical heating elements inthe boiler arranged in sets about each of such tubes to cause the waterto rise outside of the tubes and displace water at the top of the boilerfor return through the tubes.

4. A vertical boiler construction comprising in combination a shell, alarge number of vertically mounted individual heating elements for heattransfer to the water, a large number of water circulating tubes open attop and bottom and vertically mounted to extend from the bottom of thewater space to a point near but below the water level, the number ofheating elements far exceeding the number of said tubes, each of thelatter forming a central axis for a uniform spaced grouping of severalheating elements about such tube, the spaces between the heatingelements and between the heating elements and the tubes being very smallcompared to a crosssectional dimension of the shell, said arrangement ofheating elements and tubes being such as to substantially fill theboiler in cross-section below the water level whereby the heated wateris induced to rise with substantial uniformity outside of the tubes,release its steam and return to the bottom of the boiler through theinside of the tubes for reheating.

5. A vertical boiler construction comprising a cylindrical shell havingtop and bottom header members, a large number of vertical brace rodsconnecting the header members for uniform resistance to the burstingstrain, a series of vertical heating elements arranged in groups, eachone spaced about a brace tie as a center, a water circulating tubearranged on each brace rod and serving as a water circulating controlfor the heating elements grouped around such tie rod, said tubes openingat the bottom of the boiler and at the top but substantially below thewater line.

6. A vertical electric boiler comprising a shell, a plurality of spacedand independent electrical heating elements mounted vertically in theshell to procure an exceedingly large production of steam compared tothe size of the boiler, and a plurality of water circulating tubesvertically mounted in the boiler below the water level to receive thewater when it releases its steam near the water level and return itsolely by gravity to the bottom of the boiler for reheating by theheating elements, the latter being grouped about said tubes withsubstantial uniformity and in sets of several heating elements to eachtube said sets of heating elements and their associated tubes being inas large a number of groups as the space of the shell will permit.

GUSTAVE WELTER.

